It is generally known and understood, in athletic training and otherwise, that physical performance may be enhanced by the ability to deliver more oxygen to more active tissues, which in turn are the tissues which require more oxygen. What is often referred to as the bohr effect is a property of hemoglobin first described in 1904, which states that increasing concentration of protons and/or carbondioxide will reduce the oxygen affinity of hemoglobin. Increasing blood carbondioxide levels can lead to a decrease in pH because of the chemical equilibrium between protons and carbondioxide. Lower pH in the blood is suggestive of an increased carbondioxide concentration which, in turn, is suggestive of more active tissue, which requires more oxygen. According to the bohr effect, lower pH will cause delivery of greater concentrations of oxygen to the tissue. Separate and apart from the actual detailed scientific underpinning, it has long been generally known that high altitude training and training with less than optimum oxygen availability can enhance oxygen absorption capacity and, hence, athletic performance and endurance.
The use of breathing resistence training and the ability to vary the resistence, and difficulty of inhaling, is known. U.S. Pat. No. 6,554,746, to McConnell et al discloses an inspiratory muscle training device which has an opening for the passage of air to be both inhaled and exhaled and an inlet permitting air to be inhaled to enter the chamber and to pass through the opening. An adjustable valve is provided to vary the resistence to inhaling. U.S. Pat. No. 4,973,047, to Norell, discloses a therapeutic device for lung exercise which requires a mouthpiece, and has a rotatably adjustable air intake valve.
U.S. Pat. No. 4,549,543, to Moon, discloses an air filtering face mask and the concept of a flexible face piece which conforms to the shape of the face of the wearer, and is held in place by scraps or a harness device.
The prior art, however, does not provide a device, which does not require a mouth piece, or use the hands, and which further provides separate passages for inhaling and exhaling, which may be worn by a user, in intensely vigorous exercise, without impeding the nature of the exercise conducted. The present invention addresses the shortcomings of the prior art by providing a mask which conforms to the face of the user, providing a substantially airtight seal over the nasal and oral orifices, allowing free exhalation of air, without significant resistence, and a means for selectively varying the resistence of the air to be inhaled.
In athletic training, particularly in breathing resistence training, it becomes necessary and desirable to vary the amount of resistence to inhalation of air during vigorous exercise. The prior art, to the extent that it addresses the variability of air intake resistence, does so primarily by adjustable valves, which may include springs or other moving parts, or protruded valves which are twisted, all of which have the propensity to not function properly, or to be more susceptible to damage during vigorous exercise.